The invention relates to biodegradable compositions for sustained-release drug delivery and methods for administering a biologically active substance via these compositions.
Rapid advances in the fields of genetic engineering and biotechnology have led to the development of an increasing number of proteins and polypeptides that are useful as pharmaceutical agents. The development of methods for administering these new pharmaceutical agents is thus becoming increasingly important.
Most proteins have relatively short half-lives, requiring frequent administration to achieve efficacious blood levels. To increase patient convenience and to improve efficacy and safety by keeping blood levels within the therapeutic range, smoothly releasing injectable depot formulations of protein drugs are highly desirable.
Recent polymer developments have improved the ability to deliver proteins and peptides by allowing for slower and steadier release of the molecule in the patient's system. However, in many cases, the active form of the protein is difficult to formulate in biodegradable polymers. Synthetic materials, such as biodegradable hydrogels, have also been developed for use in delivering proteins. Despite the advances provided by the available polymers and hydrogels, the delivery of protein to the systemic and local circulation is still relatively rapid, in some cases too rapid to allow this route of administration to be used.